1800    The Act of Union 1800 is passed in which merges the Kingdom of Great Britain and the Kingdom of Ireland into the United Kingdom of Great Britain and Ireland.

1801    The legislative union of Kingdom of Great Britain and Kingdom of Ireland is completed to form the United Kingdom of Great Britain and Ireland.

1803    The Convention of Artlenburg leads to the French occupation of Hanover (which had been ruled by the British king).

1812    War of 1812: American frigate ''USS Constitution'' defeats the British frigate ''HMS Guerriere'' off the coast of Nova Scotia, Canada earning her nickname "Old Ironsides".

1813    War of 1812: three weeks of British raids on Fort Schlosser, Black Rock and Plattsburgh, New York begin.

1814    Washington, D.C. is burned and White House is destroyed by British forces during the War of 1812.

1815    Signing of the Kandyan Convention treaty by British invaders and the King of Sri Lanka.

1820    Cato Street Conspiracy: A plot to murder all the British cabinet ministers is exposed.

1830    Charles Grey, (2nd Earl Grey), became Prime Minister of the United Kingdom.

1831    William IV and Adelaide of Saxe-Meiningen are crowned King and Queen of the United Kingdom of Great Britain and Ireland.

1833    The United Kingdom claims sovereignty over the Falkland Islands.

1837    Queen Victoria succeeds to the British throne.

1840    The Penny Black postage stamp becomes valid for use in the United Kingdom of Great Britain and Ireland.

1854    Crimean War: France and Britain declare war on Russia.

1856    The Iranian city of Bushehr surrenders to occupying British forces.

1862    The United States and Britain agree to suppress the slave trade.

1867    Singapore becomes a British crown colony.

1873    The British steamer {{RMS|Atlantic}} sinks off Nova Scotia, killing 547.

1878    The British frigate {{HMS|Eurydice|1843|6}} sinks, killing more than 300.

1879    Anglo-Zulu War: Battle of Kambula: British forces defeat 20,000 Zulus.

1879    Cetshwayo, last king of the Zulus, is captured by the British.

1882    Britain's first electric trams run in east London.

1884    The United Kingdom ends its policy of penal transportation to New South Wales in Australia.

1895    The National Trust is founded in the United Kingdom.

1900    Second Boer War: In South Africa, 20,000 British troops invade the Orange Free State.

1902    Edward VII and Alexandra of Denmark are crowned King and Queen of the United Kingdom of Great Britain and Ireland.

1904    The French Third Republic and the United Kingdom of Great Britain and Ireland sign the ''Entente cordiale''.

1911    George V and Mary of Teck are crowned King and Queen of the United Kingdom of Great Britain and Ireland.

1914    World War I: the German colony of Togoland is invaded by French and British forces, who take it after 5 days.

1916    Easter Rebellion: Martial law in Ireland is lifted and the rebellion is officially over with the surrender of Irish nationalists to British authorities in Dublin.

1916    The Irish Nationalist and British diplomat Sir Roger Casement is sentenced to death for his part in the Easter Rising.